How to show alert if one minute is completed and stop script in minutes:seconds timer script using javascript

Question

I have a requirement of one minute timer in javascript in that as soon as 1 minute completed,Then show alert and halt script but in the code i try to change the condition but is not working,So i want after one minute alert should get and stop script

<script>
function startTimer(duration, display) {
    var timer = duration, minutes, seconds;
    setInterval(function () {
        minutes = parseInt(timer / 60, 10)
        seconds = parseInt(timer % 60, 10);

        minutes = minutes < 10 ? "0" + minutes : minutes;
        seconds = seconds < 10 ? "0" + seconds : seconds;

        display.textContent = minutes + ":" + seconds;
// alert(timer);
      if (--timer < 0) {
            timer = duration;
        }
        //   if one minute is completed show alert and stop script


    }, 1000);
}

window.onload = function () {
    var oneMinutes = 60 * 1,
        display = document.querySelector('#time');
    startTimer(oneMinutes, display);
};

</script>

Answer 1

<script>
function startTimer(duration, display) {
    var timer = duration, minutes, seconds;
    var x=setInterval(function () {
        minutes = parseInt(timer / 60, 10)
        seconds = parseInt(timer % 60, 10);

        minutes = minutes < 10 ? "0" + minutes : minutes;
        seconds = seconds < 10 ? "0" + seconds : seconds;

        display.textContent = minutes + ":" + seconds;
// alert(timer);
      if (--timer < 0) {
            timer = duration;
            alert('Timeup');
            clearInterval(x);  //script will stop and will not be execute
        }



    }, 1000);
}

window.onload = function () {
    var oneMinutes = 60 * 1,
        display = document.querySelector('#time');
    startTimer(oneMinutes, display);
};

</script>